Expandable fixation mechanism

ABSTRACT

In general, the invention is directed to a medical device implantable in a body of a patient. The device includes a housing with a plurality of collapsible fixation structures coupled to the housing, and can be in a collapsed configuration or an expanded configuration. The device assumes a collapsed configuration when in the bore of an insertion device, and assumes the expanded configuration when expelled from the insertion device into the body of the patient. The extended fixation structures engage the tissues in the body and restrict migration. One exemplary application of the invention is in the context of a microstimulator, with a pulse generator housed in the housing and one or more electrodes coupled to the housing. The fixation structures help keep the electrodes proximate to the tissues that are to receive the stimulation.

FIELD OF THE INVENTION

The invention relates to medical devices implantable in and near a humanor animal body and, more particularly, mechanisms for fixation ofmedical devices.

BACKGROUND

Many implantable medical devices include components that are deployed inparticular areas within a human or animal body. In one example, aneurostimulator deployed proximate to targeted tissue includeselectrodes that deliver an electrical stimulation therapy to the tissue.In another example, an electrical sensor deployed proximate to a musclesenses activation of the muscle. With these and other implantabledevices, it can be desirable that one or more components remainsubstantially anchored, so that the components will be less likely tomigrate from the desired site of sensing or therapy.

Devices that restrict migration of an implanted medical device or acomponent thereof are called “fixation structures.” Fixation structurescan anchor a medical device to an anatomical feature, such as an organor a bone. Fixation structures do not necessarily restrict all motion ofthe implanted device or its component, but generally reduce the motionof the device or component so that it remains proximate to a targetsite.

There have been many approaches that address fixation of medicaldevices. Some devices, such as a lead described in U.S. Pat. No.4,269,198 to Stokes, employ fixed protrusions such as tines to engagebody tissue. Other devices, such as the electrode assembly disclosed inU.S. Pat. No. 6,704,605 to Soltis et al., use a helical securingstructure. U.S. Pat. No. 5,405,367 to Schulman et al. describes the useof barbs to hold a medical device such as a micro stimulator in place.

Table 1 below lists documents that disclose some of the many devices andtechniques pertaining fixation of medical devices. Some of the devicesand techniques employ mechanical fixation structures such as tines orswellable membranes. Others employ adhesive properties to hold devicesin place.

TABLE 1 Pat. No. Inventors Title 6,714,822 King et al. Apparatus andmethod for expanding a stimulation lead body in situ 6,704,605 Soltis etal. Medical electrode assembly 6,697,676 Dahl et al. Medical electricallead having an expandable electrode assembly 6,650,921 Spehr et al.Cardiac lead with minimized inside diameter of sleeve 6,434,431 Camps etal. Intramuscular medical electrical lead with fixation member 6,240,322Peterfeso et al. System and apparatus having low profile collapsibletines 6,181,973 Ceron et al. Anchoring structures for implantableelectrodes 5,951,597 Westlund et al. Coronary sinus lead havingexpandable matrix anchor 5,837,007 Altman et al. Intracardiac leadhaving a compliant fixation device 5,545,206 Carson Low profile leadwith automatic tine activation 5,405,367 Schulman et al. Structure andmethod of manufacture of an implantable microstimulator 5,300,107 Stokeset al. Universal tined myocardial pacing lead 4,658,835 Pohndorf Neuralstimulating lead with fixation canopy formation

All documents listed in Table 1 above are hereby incorporated byreference herein in their respective entireties. As those of ordinaryskill in the art will appreciate readily upon reading the Summary of theInvention, Detailed Description of the Preferred Embodiments and Claimsset forth below, many of the devices and methods disclosed in thepatents of Table 1 may be modified advantageously by using thetechniques of the present invention.

SUMMARY OF THE INVENTION

In general, the invention is directed to fixation mechanisms forsecuring medical devices implanted within a human or animal body, aswell as medical devices incorporating such fixation mechanisms. Suchdevices can include implantable neurostimulators, implantablephysiological sensors, electrodes, and the like. When the medicaldevices are implanted, it is generally desirable that migration of animplanted device be restricted. The invention presents implantabledevices equipped with fixation mechanisms that help reduce migration.

Various embodiments of the present invention provide solutions to one ormore problems existing in the prior art with respect to fixationmechanisms for implantable medical devices. These problems include themigration of medical devices from a desired implantation site. Anadditional problem is the reduced therapeutic efficacy that may resultwhen a medical device migrates from its intended implantation site.Additional problems relate to the time and skill required in placementof conventional fixation mechanisms, such as sutures, and to the size ofconventional fixation mechanisms, which can have a bearing upontechniques for surgical implantation.

Various embodiments of the present invention are capable of solving atleast one of the foregoing problems. The invention presents a devicethat includes a housing with a plurality of collapsible fixationstructures coupled to the housing. The device can be in a collapsedconfiguration or an expanded configuration. When not acted upon by aforce, the device assumes the expanded configuration, with the fixationstructures extending away from the housing. When inserted into the boreof an insertion device, such as a needle, the fixation structures moveclose to the housing, and the device assumes the collapsedconfiguration. When the device is expelled from the insertion device,the fixation structures by their resiliency move toward their expandedpositions.

When an insertion device is used to implant the invention in the body ofa patient, the extended fixation structures engage the tissues in thebody. As a result, migration of the implanted device is restricted. Inaddition, implantation in some areas of the body causes the body togenerate fibrous tissue that adheres to the housing and the fixationstructures, thereby further anchoring the device in place.

The invention can be applied as a microstimulator, with a pulsegenerator housed in the housing and one or more electrodes coupled tothe housing. The fixation structures help keep the electrodes proximateto the target tissues, i.e., proximate to the tissues that are toreceive the stimulation. As another example, the invention can beapplied to physiological sensors.

In comparison to known fixation mechanisms, various embodiments of theinvention may provide one or more advantages. For example, the inventioncan provide reliable fixation for a variety of medical devices,including but not limited to self-contained stimulators, without theneed for sutures or other mechanisms requiring surgical placement.Rather, the fixation mechanism is generally self-deploying. Theinvention can also be adapted to work with other medical devices, suchas lead-mounted electrodes. In addition, the invention provides for asmall profile during implantation, allowing implantation to be made byless invasive techniques.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary medical device havingcollapsible fixation mechanisms in a collapsed state, according to anembodiment of the invention.

FIG. 2 is a perspective view of the device of FIG. 1 with the fixationmechanisms in an expanded state.

FIG. 3 is a perspective view of another exemplary medical device havingcollapsible fixation mechanisms in an expanded state, according to anembodiment of the invention.

FIG. 4 is a perspective view of a further exemplary medical devicehaving collapsible fixation mechanisms in an expanded state, accordingto an embodiment of the invention

FIG. 5 is a cross section of an exemplary syringe that may be used toimplant a device such as the device depicted in FIG. 1.

FIG. 6 is a block diagram of an implantable stimulator according to anembodiment of the invention.

FIG. 7 is a perspective view of a medical device with a device thatincludes a collapsible fixation mechanism according to anotherembodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 depicts an exemplary medical device 10 configured to be implantedin a human or animal body. For purposes of illustration, FIG. 1 depictsa self-contained device such as a microstimulator or a sensor. Themicrostimulator may be a neurostimulator or muscle stimulator. Thesensor may be configured to sense a variety of conditions, such aspressure, flow, temperature, fluid level, contractile force, pH,chemical concentration, or the like. Medical device 10 is self-containedin that it is not physically coupled to any other medical device by alead or other connection. Medical device 10 can, for example, receivepower from or wirelessly communicate with an external control device. Inanother embodiment, medical device 10 operates with an internal powersupply, such as a rechargeable or non-rechargeable battery. Theinvention is not limited to any particular medical device. Nor is theinvention limited to self-contained medical devices, but encompassesmedical devices that include leads or that are otherwise notself-contained.

Exemplary medical device 10 is shown in FIG. 1 in a first, collapsedconfiguration. Exemplary medical device 10 includes a substantiallycylindrical housing 12 and a plurality of collapsible fixationstructures 14 coupled to housing 12. In the example of medical device10, there are eight fixation structures 14 and fixation structures 14are tines. The invention encompasses devices that include more thaneight tines. For example, housing 12 could accommodate an additionalfour tines in the center of housing 12, offset from the eight tines thatare shown.

In FIG. 1, fixation structures 14 are folded against housing 12. In thiscollapsed configuration, the dimensions of device 10 can be selectedsuch that device 10 can fit inside the bore of an insertion device, suchas needle, hollow trocar, endoscope, catheter or cannula. In particular,device 10 can fit through a bore or sleeve oriented substantiallyparallel to long axis 16. Dimensions of housing 12 can be approximatelyone to seven millimeters in diameter (transverse to axis 16) and ten totwenty millimeters in length (parallel to axis 16). The inventionencompasses other shapes and dimensions as well. The dimensions ofmedical device 10 can depend upon the internal components of medicaldevice 10. In FIG. 1, for example, medical device 10 can embody astimulating device, such as a neurostimulator, that delivers electricalstimulations to target tissue via electrodes 18 and 20. Housing 12 issized to receive the components of a stimulator, such as a pulsegenerator, wireless telemetry interface, and a power supply.

FIG. 2 shows exemplary medical device 10 in a second, expandedconfiguration. The expanded configuration is the configuration thatmedical device 10 assumes unless acted upon by a force, such as thereactive force asserted by the bore of an insertion device. As a result,when medical device 10 is expelled in its collapsed state from theinsertion device, fixation structures 14 by their resiliency move towardthe expanded configuration. It is possible that contact with tissues inthe patient's body can prevent fixation structures 14 from becomingfully expanded as depicted in FIG. 2, but it is not necessary that thefixation structures 14 be fully expanded to be effective. As usedherein, the “expanded configuration” includes configurations in whichfixation structures 14 are wholly or partially expanded.

In the expanded configuration, medical device 10 fixation structures 14have extended away from axis 16. When extended, fixation structures 14are more likely to engage surrounding tissue, thereby restrictingmigration of medical device 10. In addition, deployment of medicaldevice 10 in some sites in the body of the patient causes the body togenerate fibrous tissue that adheres to housing 12 and fixationstructures 14, thereby further anchoring device 10 in place. In thecontext of a stimulation device, extension of fixation structures 14helps hold electrodes 18 and 20 proximate to the target tissues.

Housing 12 can be constructed of any biocompatible material, such assilicone, polyurethane, titanium, stainless steel, fluoropolymer andhydrogel. Housing 12 can also be constructed of another material, andsealed inside an envelope of biocompatible material. Fixation structures14 likewise can be constructed of one or more biocompatible materialssuch as silicone, polyurethane, titanium, stainless steel, fluoropolymerand hydrogel. In one embodiment of the invention, fixation structures 14are formed from a flexible material such as a flexible polymer or metal,and are coupled to housing 12 in the fully expanded position. Wheninserted into the bore of an insertion device, fixation structures 14fold down toward housing 12, as shown in FIG. 1. When ejected from theinsertion device, fixation structures 14 by their resiliency move towardtheir fully expanded positions. When fully extended, fixation structures14 may project one to seven millimeters from housing 12. In actual use,structures such as body tissues proximate to device 10 may preventfixation structures 14 from achieving the fully expanded configuration.

Fixation structures 14 can be coupled to housing 12 in any manner, suchas by adhesive, welding, bonding or interlocking In some embodiments ofthe invention, fixation structures 14 can be formed integrally withhousing 12.

In a variation, fixation structures 14 can be constructed from abiocompatible hydrogel material. Hydrogel materials that are believed tohave wide applicability are the polyacrylonitrile copolymers asdescribed in U.S. Pat. Nos. 4,943,618 and 5,252,692, which areincorporated herein by reference. By controlling relative amounts ofcopolymers, it is often possible to regulate physical qualities of thehydrogel such as flexibility and amount of expansion. In general,hydrogels can assume a dehydrated state and a hydrated state. A hydrogelelement in its dehydrated state is generally substantially smaller thanthe element in its hydrated state. A hydrogel element in its dehydratedstate, when implanted in the body of a patient and placed in contactwith body fluids, absorbs water and expands, assuming a hydrated state.Fixation structures 14 made of hydrogel can be coupled to housing 12,and can expand outward and can expand in size when they come in contactwith bodily fluids.

Medical device 10 is directionally oriented, with a distal end 22 and aproximal end 24. The portions of tines 14 closest to distal end 22 areaffixed to housing 12, and the portions of tines 14 closest to proximalend 24 extend away from housing 12. When medical device 10 is inserted,distal end 22 first, into the bore of an insertion device, tines 14 folddown and medical device 10 assumes a collapsed configuration.

FIG. 3 is a perspective view of an exemplary medical device 30 in whichthe fixation structures are not directionally oriented. Like medicaldevice 10, medical device 30 includes a housing 32. Medical device 30also includes a plurality of fixation structures 34. Fixation structures34 are tines or spurs that extend outward substantially orthogonallyfrom device axis 34. FIG. 3 shows device 30 in a fully expandedconfiguration.

Although medical device 30 has thirty-six tines, the inventionencompasses devices having more or fewer tines. Smaller tines can bemore flexible than larger tines, and there can be advantages to using alarger number of small tines instead a smaller number of large tines. Inaddition, medical device has tines arranged in a regular pattern, butthe invention supports fixation structures arrayed in an irregularfashion as well.

Housing 32 can be constructed of the same materials as, and havedimensions comparable to, housing 12. Fixation structures 34 can beconstructed of the same materials as, and extend as far from the housingas, fixation structures 12. Fixation structures 34, however, are shownas having a thinner profile than fixation structures 12, so thatfixation structures 32 can bend toward one end of device 30 or theother.

Medical device 30 need not have distinct proximal and distal ends. Whenmedical device 30 is inserted into the bore of an insertion device,tines 34 fold down, and medical device 10 assumes a collapsedconfiguration. Device 30 would also assume a collapsed configuration ifdevice 30 were turned end for end and inserted into the bore of theinsertion device.

FIG. 4 is a perspective view of another exemplary embodiment of theinvention. Medical device 40 includes a housing 42 and a plurality offixation structures 44. Fixation structures 44 are flanges that extendoutward substantially orthogonally from device axis 44. FIG. 4 depictsthree flanges, but the invention encompasses devices having more orfewer flanges as well. FIG. 4 shows device 40 in an expandedconfiguration.

Like device 30, device 40 includes fixation structures 44 that are notdirectionally oriented. Either end of medical device 40 could beinserted into the bore of an insertion device, and flanges 44 fold down.

As depicted in FIG. 4, flanges 44 comprise a plurality of ribs 48 withwebbing 50 deployed between ribs 48. Webbing 50 may be thinner and morepliable than ribs 48, which can aid in folding of flanges 44. Ribs 48also protrude farther from axis 46 than webbing 50, which can enhanceengagement with fibrous tissue and thereby promote fixation. Ribs 48 andwebbing 50 may be, but need not be, constructed from the same material.Although device 40 has eighteen ribs 48, the invention supportsembodiments in which there are more or fewer ribs. In somecircumstances, there can be advantages to using a larger number of smallribs instead a smaller number of large ribs.

The invention supports embodiments in which flanges do not have ribs andwebbing, but have a uniform thickness. The invention also supportsembodiments in which fixation structures comprise one or more differenttypes of fixations structures. A medical device may include, forexample, both tines and flanges. The fixation structures need not beuniform in size. For example, some tines can be longer than others.

FIG. 5 is a cross-sectional diagram of an illustrative insertion device60 that can implant a medical device such as medical device 10 in apatient. Device 60 comprises a syringe, which includes a plunger member62, a body member 64 and a hollow needle 66 having a bore or lumen 68.Needle 66 is fixedly coupled to body member 64, while plunger member 62is free to move in lumen 68. Lumen 68 of needle 66 has been enlarged toshow medical device 10, in a collapsed configuration, disposed in lumen68. As depicted in FIG. 5, medical device 10 in the collapsedconfiguration is an elongated device, shaped substantially like a grainof rice, and sized to fit inside lumen 68. Before placement of medicaldevice 10 into lumen 68, medical device 10 is in an expandedconfiguration. Placement of medical device 10 into lumen 68 causesmedical device 10 to assume the collapsed configuration.

Distal end 70 of needle 66 includes a sharp point that can pierce tissuesuch as the skin, the mucosa of the gastrointestinal tract, a body organor a tissue mass. Distal end 70 further includes an opening throughwhich medical device 10 may be expelled from lumen 68 by depressingplunger member 62 with respect to body member 64.

Device 60 is not the only insertion device that can be used to implant amedical device such as medical device 10. For example, a physician canimplant medical device 10 by making an incision in the skin, introducingan insertion device such as a catheter into the body of the patient,guiding the insertion device to a target site, pushing medical device 10through the insertion device, and withdrawing the insertion device.

In general, implantation of a medical device in a collapsedconfiguration is less invasive than a surgical procedure to implant themedical device in its expanded configuration. The medical device can bedelivered to a target site in a collapsed configuration, and expand onits own to its expanded configuration.

FIG. 6 is a block diagram of an exemplary medical device 80 that canemploy many of the features described above. Medical device 80 is anexample of a self-contained implantable stimulator. Stimulator 80includes pulse generator 82, which supplies electrical stimulations tothe target tissue via electrodes 84, 86, which are exposed to thetissue. Pulse generator 82 supplies stimulations under the direction ofprocessor 88. Processor 88 may comprise a microprocessor, applicationspecific integrated circuit, a programmable logic chip, or othercontrolling circuitry.

A power supply 90, such as a capacitor or a battery, supplies power topulse generator 82 and processor 88. In the embodiment depicted in FIG.6, medical device 80 includes an inductive coil 92 configured to receiveenergy from an external energy source. Medical device 80 also includes awireless telemetry interface 94 configured to wirelessly transmit orreceive data or instructions. Pulse generator 82, processor 88, powersupply 90, coil 92 and wireless telemetry interface 94 are housed insidehousing 96.

Fixation structures 98 extend toward an extended position when medicaldevice 80 is implanted in the body of a patient. Extension of fixationstructures 98 restricts migration of medical device 80. As a result,electrodes 84, 86 tend to remain proximate to the target tissue.

Medical device 80 can include components other than or in addition tothe components depicted in FIG. 6. For example, medical device 80 canincorporate an accelerometer or a sensor, such as a sensor configured tosense conditions such as pressure, flow, temperature, fluid level,contractile force, pH or chemical concentration. The invention is notlimited to the specific embodiment depicted in FIG. 6.

In addition, FIG. 6 depicts electronic components such as electrodes ashoused inside housing 96. The invention also supports embodiments inwhich one or more components are deployed on or in fixation structures98. For example, an electrode can be deployed on the surface of afixation structure such that the electrode moves away from housing 96when the fixation structure moves to an expanded configuration.

FIG. 7 is a perspective drawing of a further embodiment of theinvention. Extending element 100 is an elongated element having aproximal end 102 and a distal end 104. Distal end is coupled to amedical device 106, which may be an implantable medical device. Medicaldevice 106 can be, for example, a stimulator configured to supplyelectrical stimulation therapy to target tissue, a drug pump thatdelivers drugs to a target site, or a sensor that senses parameters suchas blood pressure, temperature, or electrical activity. The function ofextending element 100 depends upon the function of medical device 106.When medical device 106 represents a drug pump and a reservoir for thedrugs being delivered, for example, extending element 100 represents oneor more catheters that administer the drugs to the cells, with distalend 104 being deployed proximate to the cells of concern.

For purpose of illustration, FIG. 7 depicts medical device 106 as astimulator configured to deliver electrical stimulation to target tissuevia electrodes 108. Extending element 100 is a lead that conductsstimulations generated by stimulator 106 to electrodes 108.

Lead 100 includes fixation mechanism 110. In FIG. 7, fixation mechanism110 is similar to medical device 30 in FIG. 3, in that fixationmechanism 110 includes a plurality of tines or spurs 112 that protrudefrom a housing 114 and that operate as fixation structures. Unlikemedical device 30, however, fixation mechanism 110 is not aself-contained medical device. Fixation mechanism 110 holds electrodes108 proximate to the target tissue to be stimulated.

Fixation mechanism 110 can be integrally formed with distal end of lead104. For example, a portion of distal end 104, may be encased insilicone, and tines 112 and housing 114 can be made of the samematerials. In another embodiment, fixation mechanism 110 can be embodiedas a hollow sleeve sized to fit over a portion of distal end of lead104.

Lead 100 can be deployed in a catheter according to conventionaldeployment procedures, with tines 112 in a collapsed configuration. Whendistal end 104 is proximate to the target tissue, the catheter can bewithdrawn and tines 112 can expand to the extended configuration. Insome implantations, lead 100 is disconnected from medical device 106during deployment, and is coupled to medical device 106 afterdeployment.

Tines 112 of fixation mechanism 110 resist migration of distal end 104.In some deployments, the patient can naturally develop fibrous tissuearound tines 112, which further promote anchoring of distal end 104 nearthe target tissue.

The preceding specific embodiments are illustrative of the practice ofthe invention. It is to be understood, therefore, that other expedientsknown to those skilled in the art or disclosed herein may be employedwithout departing from the invention or the scope of the appendedclaims. For example, the invention is not limited to an implant havingthe shape and illustrative dimensions described above.

Furthermore, the invention is not limited to the particular shapes offixation structures elements depicted in the figures. Tines 14 in FIGS.1 and 2, and tines 34 in FIG. 3 are depicted as having substantiallyrectangular cross-sections, but the invention supports fixationstructures having other cross-sectional shapes. In addition, theinvention encompasses embodiments in which the fixation structuresextend further in one direction than in another.

Although the invention is described as useful in application with theneurostimulation, the invention is not limited to that application.Furthermore, the invention can be deployed via implantation techniquesin addition to those described above. The invention further includeswithin its scope methods of making and using the implants describedabove.

In the appended claims, means-plus-function clauses are intended tocover the structures described herein as performing the recited functionand not only structural equivalents but also equivalent structures.Thus, although a nail and a screw may not be structural equivalents inthat a nail employs a cylindrical surface to secure wooden partstogether, whereas a screw employs a helical surface, in the environmentof fastening wooden parts a nail and a screw are equivalent structures.

Many embodiments of the invention have been described. Variousmodifications may be made without departing from the scope of theclaims. These and other embodiments are within the scope of thefollowing claims.

1. A system comprising: an elongated element configured to be coupled toa medical device to deliver a therapy from the medical device to targettissue in a patient; and a plurality of hydrogel fixation structuresextending from the elongated element and configured to expand from adehydrated state to a hydrated state, wherein in the hydrated state, atleast two of the hydrogel fixation structures radially extend from theelongated element in different directions.
 2. The system of claim 1,wherein in the hydrated state, each of the hydrogel fixation structuresextends from the elongated element at an acute angle with respect to alongitudinal axis of the elongated element.
 3. The system of claim 1,wherein in the hydrated state, each of the hydrogel fixation structuresextends substantially orthogonally from a longitudinal axis of theelongated element.
 4. The system of claim 1, wherein the elongatedelement comprises a lead comprising an electrode.
 5. The system of claim4, further comprising the medical device, wherein the medical device isconfigured to deliver electrical stimulation to the target tissue viathe electrode.
 6. The system of claim 4, further comprising the medicaldevice, wherein the medical device is configured to sense a parameter ofa patient via the electrode.
 7. The system of claim 6, wherein theparameter comprises at least one of blood pressure, temperature orelectrical activity of the patient.
 8. The system of claim 1, whereinthe elongated element comprises a catheter.
 9. The system of claim 8,further comprising the medical device, wherein the medical devicecomprises a drug delivery pump configured to deliver a drug to thetarget tissue via the catheter.
 10. The system of claim 1, wherein eachof the plurality of hydrogel fixation structures defines at least one ofa tine, a spur, a flange or a rib in the hydrated state.
 11. The systemof claim 1, further comprising a sleeve sized to fit over a portion ofthe elongated element, wherein at least one of the hydrogel fixationstructures is attached to the sleeve.
 12. The system of claim 1, whereinthe plurality of hydrogel fixation structures comprises a first hydrogelfixation structure and a second hydrogel fixation structure axiallydisplaced from the first hydrogel fixation structure.
 13. A methodcomprising: implanting a medical system in a patient, the medical systemcomprising: an elongated element being configured to be coupled to amedical device to deliver a therapy from the medical device to targettissue in a patient; and a plurality of hydrogel fixation structuresextending from the elongated element and configured to expand from adehydrated state to a hydrated state, wherein in the hydrated state, atleast two of the hydrogel fixation structures radially extend from theelongated element in different directions.
 14. The method of claim 13,further comprising: implanting the medical device in the patient; andcoupling the medical device and the elongated element.